Using Toluates as Simple and Versatile Radical Precursors
Kevin Lam and István E. Markó
*Département de Chimie, Bâtiment Lavoisier, Université catholique de Louvain, Place Louis Pasteur, 1, B-1348 Louvain-la-Neuve, Belgium, Email: istvan.markouclouvain.be
K. Lam, I. E. Markó, Org. Lett., 2008, 10, 2919-2922.
DOI: 10.1021/ol800944p (free Supporting Information)
see article for more reactions
A new, easy and versatile methodology for the deoxygenation of alcohols via the corresponding toluates offers a broad scope using simple and commercially available reagents such as toluolyl chloride and samarium(II) iodide. In addition, this methodology is also useful for radical cyclizations directly from toluate precursors.
see article for more examples
Some benefits of the method:
- Aromatic esters are very robust and totally stable compared to xanthates or to some sulfonates. They can be stored on bench for years.
- Very often, toluates are solids which can be recrystallised in a mixture of EtOH/water without hydrolysis or transesterification.
- Using toluoyl chloride/TMEDA, esterification is finished within 30 minutes (see Org. Lett., supporting information).
- The deoxygenation using SmI2/HMPA/THF is almost instantaneous (few seconds)!
- The corresponding samarium carboxylate side product can easily be isolated by acid base extraction and reused for esterification.
Kevin Lam, December 22, 2009
K. Lam, I. E. Markó, Chem. Commun., 2009, 95-97.